My HDVR2 has a tuner that is gone/going bad. When using the particular tuner, I'm getting intermittent but heavy pixelation.

I took a look inside and found.


Those two caps 220mf 3.5w are significantly hotter that the matching pair in the other tuner. (finger test)

So am I too far off base thinking that those caps are being stressed and replacing them would solve my problem. They don't appear to have leaked or bulged.

They seem to be surface mounted, So I don't expect to have to remove the board from the chassis.

Before you remove them, you might try and measure the DC voltage going to each of them. It probably should be identical in both circuits.

-ml

I get either 17 or 23v. But that changes depending on which channel is being watched. That would seem to make these related to the selection of LNB polarization.

I'm guessing that this shouldn't be a cause of the pixelation, unless maybe the LNB is being switched when it shouldn't, causing dropouts.

Further web searching yielded numerous threads about power supply problems causing pixelation or crashing. There are also reports of marginal supplies causing problems, on one tuner, when an additional output like composite out or svideo is connected.

Good. Neither 17V nor 23V exceeds the 35V rating on those caps, so they may simply have gone bad somehow.

Cheers

That's more likely 35V (as in volts, not watts).
What makes you think the caps have a wattage rating?

Cheers

If the pixellation is repeatable, can you pull up a signal strength page while it's happening. Does the signal drop significantly when it happens? What about swapping your feeds over? Maybe you have a cable or LNB fault that's causing those caps to warm up?

I saw the markings an recognized 220 as a common value, if the voltage (first line) had been marked with a V, I'd have most likely ignored the third line.

Yes I'm guilty of specializing in mechanical design with a bare minimum of formal electronics training.

I had a semester of electronics in High School in 1973. To be honest I learned enough to pass, to be able to build the average kit, recognize all the parts, but not quite enough to be more than a shade tree troubleshooter.

I was able to determine that one tuner was giving trouble over the other. Recordings made from poor signals always play back with the exact same errors. Dying drives don't playback errors reliably.

Actually I'm relearning that I should be more suspicious of the power supply. I had a S1 tivo that was cured of random crashes/reboots by replacing the power supply.

Okay. Caps like those generally have a Voltage rating, and a temperature rating, in addition to the actual capacitance value.

Generally, you want the temperature rating as high as you can get (eg. 85 degrees C or more). The 35V voltage rating is fine (higher than either possible input voltage).

If you feel you can successfully remove/replace the existing caps, then there's no downside to doing so.

Cheers